def user_sum(num1, num2):
    # num1和num2是形参
    print(f"求和结果{num1 + num2}")


# 3和5是实参
ret = user_sum(3, 5)
# 若函数中未指明返回的结果，则默认返回None,类似于C中的void
print(ret) #返回结果：None


def user_sum_two(num1, num2):
    # num1和num2是形参
    result = num1 + num2
    print(f"求和结果{result}")
    return result


ret1=user_sum_two(3,5)
# 函数中指明返回值
print(ret1)          #返回结果：8
print(type(ret1))    #返回类型：<class 'int'>

ret2=user_sum_two("abc","def")
# 函数中指明返回值
print(ret2)          #返回结果：8
print(type(ret2))    #返回类型：<class 'int'>

def test1():
    print("*" * 50)
    print("test 1")
    print("*" * 50)

# test1()


def test2():
    print("-" * 50)
    print("test 2")
    test1()
    print("-" * 50)


test2()